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Conventional fluorescent tubes are increasingly being replaced with innovative light-emitting diodes (LEDs) for lighting poultry houses. However, little is known about whether the flicker frequencies of LED luminaires are potential stressors in poultry husbandry. The term “light flicker” describes the fluctuations in the brightness of an electrically operated light source caused by the design and/or control of the light source. In this context, the critical flicker frequency (CFF) characterizes the frequency at which a sequence of light flashes is perceived as continuous light. It is known that CFF in birds is higher than that in humans and that light flicker can affect behavioral patterns and stress levels in several bird species. As there is a lack of knowledge about the impact of flicker frequency on fattening turkeys, this study aimed to investigate the effects of flicker frequency on the behavior, performance, and stress response in male turkeys. In 3 trials, a total of 1,646 male day-old turkey poults of the strain B.U.T. 6 with intact beaks were reared for 20 wk in 12 barn compartments of 18 m² each. Each barn compartment was illuminated using 2 full-spectrum LED lamps. Flicker frequencies of 165 Hz, 500 Hz, and 16 kHz were set in the luminaires to illuminate the compartments. Analyses of feather corticosterone concentration were performed on fully grown third-generation primaries (P 3) of 5 turkeys from each compartment. No significant differences were found in the development of live weight, feed consumption, or prevalence of injured or killed turkeys by conspecifics reared under the above flicker frequencies. The flicker frequencies also did not significantly influence feather corticosterone concentrations in the primaries of the turkeys. In conclusion, the present results indicate that flicker frequencies of 165 Hz or higher have no detrimental effect on growth performance, injurious pecking, or endocrine stress response in male turkeys and, thus, may be suitable for use as animal-friendly lighting.

The European Union (EU) began developing climate policy in the 1990s. Since then, it has built up a broad portfolio of mitigation policy measures and governance tools, including legally binding targets to reduce greenhouse gas (GHG) emissions, and policy measures addressing emissions trading, renewable energy, energy efficiency, and more. In 2019, the European Commission—the EU's executive arm—published the European Green Deal (EGD), an overarching policy framework to achieve the goal of climate neutrality by 2050. The EGD aims to push EU climate policy and governance far beyond incremental policy development. In this article, we ask: does the EGD represent a break from past patterns of EU climate governance? We argue that it maintains several past patterns, but nevertheless breaks from other established policy and governance trends. We review insights from politicization and new institutionalist theoretical lenses to help us understand these findings. We reveal certain tensions and challenges inherent in the EU's climate governance approach—around speed and coherence, effectiveness and just transition—that highlight future research needs, and raise questions about the EU's ability to implement its climate policy goals. This article is categorized under:Policy and Governance > Multilevel and Transnational Climate Change Governance A timeline of three decades of evolving climate policy in the European Union, including renewable energy, energy efficiency, emissions trading and other policies, until the European Green Deal that was published in 2019.

The National Cancer Institute Imaging Data Commons is part of the broader Cancer Research Data Commons infrastructure that hosts publicly available cancer imaging data co-located with analysis and exploration resources, with strong emphasis on data harmonization, establishing best practices for cancer imaging data management, and developing use cases to support transparent, reproducible, and scalable imaging research.

Deep convective transport of gaseous precursors to ozone (O3) and aerosols to the upper troposphere is affected by liquid phase and mixed‐phase scavenging, entrainment of free tropospheric air and aqueous chemistry. The contributions of these processes are examined using aircraft measurements obtained in storm inflow and outflow during the 2012 Deep Convective Clouds and Chemistry (DC3) experiment combined with high‐resolution (dx≤3 km) WRF‐Chem simulations of a severe storm, an air mass storm, and a mesoscale convective system (MCS). The simulation results for the MCS suggest that formaldehyde (CH2O) is not retained in ice when cloud water freezes, in agreement with previous studies of the severe storm. By analyzing WRF‐Chem trajectories, the effects of scavenging, entrainment, and aqueous chemistry on outflow mixing ratios of CH2O, methyl hydroperoxide (CH3OOH), and hydrogen peroxide (H2O2) are quantified. Liquid phase microphysical scavenging was the dominant process reducing CH2O and H2O2outflow mixing ratios in all three storms. Aqueous chemistry did not significantly affect outflow mixing ratios of all three species. In the severe storm and MCS, the higher than expected reductions in CH3OOH mixing ratios in the storm cores were primarily due to entrainment of low‐background CH3OOH. In the air mass storm, lower CH3OOH and H2O2scavenging efficiencies (SEs) than in the MCS were partly due to entrainment of higher background CH3OOH and H2O2. Overestimated rain and hail production in WRF‐Chem reduces the confidence in ice retention fraction values determined for the peroxides and CH2O. Methyl hydroperoxide mixing ratios are decreased mainly by entrainment and liquid phase and mixed‐phase scavengingHydrogen peroxide and formaldehyde mixing ratios affected more by liquid phase scavenging than by entrainment or aqueous chemistryOverestimated rain/hail production in WRF‐Chem reduces confidence in ice retention fraction values determined for peroxides and formaldehyde

Water vapor's contribution to Earth's radiative forcing is most sensitive to changes in its lower stratosphere concentration. One recognized pathway for rapid increases in stratospheric water vapor is tropopause‐overshooting convection. Since this pathway has been rarely sampled, the NASA Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) field project focused on obtaining in situ observations of stratospheric air recently affected by convection over the United States. This study reports on the extreme altitudes to which convective hydration was observed. The data show that the overworld stratosphere is routinely hydrated by convection and that past documented records of stratospheric heights of convective hydration were exceeded during several DCOTSS flights. The most extreme event sampled is highlighted, for which stratospheric water vapor was increased by up to 26% at an altitude of 19.25 km, a potential temperature of 463 K, and an ozone mixing ratio >1500 ppbv. When thunderstorms reach into the second layer of the atmosphere above Earth's surface, the stratosphere, they may impact the concentration and distribution of trace gases that are important to chemistry and climate. One gas that is routinely affected during these events is water vapor, which is typically scarce in the stratosphere. This study presents new aircraft observations of extreme heights in the stratosphere moistened by these thunderstorms. Since increases in stratospheric water vapor positively contribute to warming of Earth's climate and can activate chemistry that destroys ozone, better understanding of this phenomenon helps refine our understanding of its role in the climate system. The new aircraft observations provide clear evidence that water vapor is enhanced by thunderstorms at higher levels in the stratosphere than previously recognized. Tropopause‐overshooting convection in the United States hydrates the stratosphere to exceptional heightsObservations of the height of stratospheric convective hydration during the Dynamics and Chemistry of the Summer Stratosphere field campaign exceed all prior global recordsThe overworld stratosphere is routinely hydrated by midlatitude overshooting convection Tropopause‐overshooting convection in the United States hydrates the stratosphere to exceptional heights Observations of the height of stratospheric convective hydration during the Dynamics and Chemistry of the Summer Stratosphere field campaign exceed all prior global records The overworld stratosphere is routinely hydrated by midlatitude overshooting convection

Stratosphere‐troposphere exchange (STE) is important to the global radiation budget because it is capable of inducing significant changes in trace greenhouse gases such as ozone and water vapor. In the extratropics, stratosphere‐to‐troposphere—or downward—transport (STT) dominates and is routinely driven by upper‐troposphere jet circulations and cyclones. Tropopause‐overshooting convection provides a more rapid STE pathway, but STT in convection is less understood and targeted observations are limited to a handful of fortuitous aircraft encounters. In this study, we seek to improve understanding of STT near thunderstorm anvils using balloon observations of ozone, ground‐based radar observations, visible satellite imagery, and model output. Radar and satellite imagery are used to identify and ultimately target convection driving the “ozone‐wrapping” process. Herein, observations from a single mesoscale convective system in central Oklahoma are reported. A significant ozone enhancement 40%–60% greater than background concentrations in the free troposphere was observed during the balloon ascent underneath and within the anvil of the storm. Backwards particle trajectories were calculated to rule out other sources of this feature such as long‐range transport of stratospheric air and smoke pollution from nearby wildfires. To our knowledge, this work presents the first targeted ozonesonde launch and sampling of this STT process. Ozone is an important greenhouse gas in the atmosphere that contributes to global climate change. Thunderstorms are one of many processes that transport stratospheric air (high in ozone) to the troposphere, but few studies examine the extent to which thunderstorms impact ozone concentrations in the upper troposphere via this process. In this study, we use novel balloon observations of ozone and additional observations of a storm and its environment to measure ozone change in the upper troposphere. During the passage of a large thunderstorm complex in central Oklahoma on 2 May 2022, our balloon observations measured significant ozone enhancement 40%–60% greater than background concentrations near the periphery of the storm in the upper troposphere. Other potential sources of this feature such as long‐range transport of stratospheric air and smoke pollution from nearby wildfires were ruled out. To our knowledge, this work presents the first targeted balloon launch and sampling of high ozone in the troposphere that was transported from the stratosphere by a thunderstorm. The first known successful balloon sampling of the anvil wrapping stratosphere‐to‐troposphere transport process in midlatitude convectionOzone enhancements within the observed anvil wrapping are 40%–60% greater than background troposphere concentrationsSimilar ozone enhancements are found within the observed storm anvil The first known successful balloon sampling of the anvil wrapping stratosphere‐to‐troposphere transport process in midlatitude convection Ozone enhancements within the observed anvil wrapping are 40%–60% greater than background troposphere concentrations Similar ozone enhancements are found within the observed storm anvil

Convection that penetrates the tropopause (overshooting convection) rapidly transports air from the lower troposphere to the lower stratosphere, potentially mixing air between the two layers. This exchange of air can have a substantial impact on the composition, radiation, and chemistry of the upper troposphere and lower stratosphere (UTLS). In order to improve our understanding of the role convection plays in the transport of trace gases across the tropopause, this study presents a 10 year analysis of overshooting convection for the eastern two thirds of the contiguous United States for March through August of 2004 to 2013 based on radar observations. Echo top altitudes are estimated at hourly intervals using high‐resolution, three‐dimensional, gridded, radar reflectivity fields created by merging observations from available radars in the National Oceanic and Atmospheric Administration Next Generation Weather Radar (NEXRAD) network. Overshooting convection is identified by comparing echo top altitudes with tropopause altitudes derived from the ERA‐Interim reanalysis. It is found that overshooting convection is most common in the central United States, with a weak secondary maximum along the southeast coast. The maximum number of overshooting events occur consistently between 2200 and 0200 UTC. Most overshooting events occur in May, June, and July when convection is deepest and the tropopause altitude is relatively low. Approximately 45% of the analyzed overshooting events (those with echo tops at least 1 km above the tropopause) have echo tops extending above the 380 K level into the stratospheric overworld. A new analysis of NEXRAD radar data shows the spatial and temporal occurrence of tropopause‐overshooting convection over the United StatesTen years of high‐resolution gridded NEXRAD data (GridRad) are now available through the NCAR Research Data ArchiveOvershooting convection is most common over the central United States; almost half of observed overshooting events reach 380 K or higher

On 27 August 2013, during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys field mission, NASA's ER‐2 research aircraft encountered a region of enhanced water vapor, extending over a depth of approximately 2 km and a minimum areal extent of 20,000 km2in the stratosphere (375 K to 415 K potential temperature), south of the Great Lakes (42°N, 90°W). Water vapor mixing ratios in this plume, measured by the Harvard Water Vapor instrument, constitute the highest values recorded in situ at these potential temperatures and latitudes. An analysis of geostationary satellite imagery in combination with trajectory calculations links this water vapor enhancement to its source, a deep tropopause‐penetrating convective storm system that developed over Minnesota 20 h prior to the aircraft plume encounter. High resolution, ground‐based radar data reveal that this system was composed of multiple individual storms, each with convective turrets that extended to a maximum of ~4 km above the tropopause level for several hours. In situ water vapor data show that this storm system irreversibly delivered between 6.6 kt and 13.5 kt of water to the stratosphere. This constitutes a 20–25% increase in water vapor abundance in a column extending from 115 hP to 70 hPa over the plume area. Both in situ and satellite climatologies show a high frequency of localized water vapor enhancements over the central U.S. in summer, suggesting that deep convection can contribute to the stratospheric water budget over this region and season. A plume containing highly elevated water vapor concentrations was observed in situ in the stratosphere over the U.S. in summerUsing a combination of diverse data sets, the observed enhancement in stratospheric humidity is linked to a deep convective storm systemThe quantity of water vapor irreversibly delivered to the lower stratosphere by this convective storm system is calculated

Convective clouds are important for both the vertical redistribution of tropospheric trace gases and the removal, via microphysical scavenging, of soluble trace gas precursors of ozone. We investigate wet scavenging of formaldehyde (CH2O), hydrogen peroxide (H2O2), and methyl hydrogen peroxide (CH3OOH) in quasi‐marine and land convective storms over Texas, USA observed on 18 September 2013 during the 2013 SEAC4RS campaign. Cloud‐resolving simulations using the Weather Research and Forecasting model with Chemistry (WRF‐Chem) were performed to understand the effect of entrainment, scavenging efficiency (SE), and ice physics processes on these trace gases with varying solubility. While marine and land convection can have distinctly different microphysical properties, we did not find significant differences in the SEs of CH2O, H2O2, or CH3OOH. The SEs of 44%–53% for CH2O and 85%–90% for H2O2are consistent with our previous studies from SEAC4RS and the 2012 DC3 field experiment storms. Using WRF‐Chem simulations, the ice retention factor (rf) for CH2O was determined to be 0.5–0.9, which is higher than found in previous studies. We show that the CH2O rfis higher in airmass and multicell storms than in severe storms and hypothesize that ice shattering may affect CH2O rfvalues. The CH3OOH SEs (39%–73%) were higher than expected from Henry's Law equilibrium. While recent studies suggest that CH3OOH measurements have interference due to methane diol, we find that this interference cannot fully explain the higher‐than‐expected CH3OOH SEs determined here and during DC3, suggesting further research is needed to understand CH3OOH vertical redistribution. Thunderstorms are important mechanisms for the transport and removal of trace gases in the atmosphere. This study investigates the transport and removal processes of tropospheric ozone trace gas precursors in marine and land convective storms over Texas, USA. Numerical simulations were performed to understand storm processes affecting atmospheric gases with different solubilities. While marine and land storms can have distinctly different storm structure and updraft winds, we did not find significant differences in the amount of gases removed by these storms. The results show that the efficiency of the storm in removing gas from the atmosphere is consistent with our previous findings for moderate to severe storms over the US. In addition, the analysis showed when cloud drops freeze onto ice and snow particles that formaldehyde had more retention in the frozen particle in moderate storms compared to severe storms suggesting that there are many processes affecting this key ozone precursor in deep convection. The more soluble hydrogen peroxide did not show the same ice retention behavior because it is removed by precipitation in the warmer, liquid‐only region of the storm. Although marine and land convection have different microphysical properties, there are no relevant differences in the scavenging efficiencyWRF‐Chem simulations analysis shows ice retention factor for formaldehyde is higher than found in previous studiesMethyl hydrogen peroxide scavenging efficiencies are higher than expected from Henry's Law, even with potential measurement interference Although marine and land convection have different microphysical properties, there are no relevant differences in the scavenging efficiency WRF‐Chem simulations analysis shows ice retention factor for formaldehyde is higher than found in previous studies Methyl hydrogen peroxide scavenging efficiencies are higher than expected from Henry's Law, even with potential measurement interference